diff --git a/.isort.cfg b/.isort.cfg
index 2b28db04..7a30df96 100644
--- a/.isort.cfg
+++ b/.isort.cfg
@@ -20,3 +20,5 @@ src_paths =
     cyclonedx
     tests
     typings
+    examples
+    tools
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 75fb111b..b8b34b7a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -5,8 +5,6 @@ But please read the
 [CycloneDX contributing guidelines](https://github.com/CycloneDX/.github/blob/master/CONTRIBUTING.md)
 first.
 
-See also: [contrib docs](docs/contributing.rst)
-
 ## Setup
 
 This project uses [poetry]. Have it installed and setup first.
diff --git a/cyclonedx/exception/__init__.py b/cyclonedx/exception/__init__.py
index dc915bfb..1845b006 100644
--- a/cyclonedx/exception/__init__.py
+++ b/cyclonedx/exception/__init__.py
@@ -25,3 +25,8 @@ class CycloneDxException(Exception):
     Root exception thrown by this library.
     """
     pass
+
+
+class MissingOptionalDependencyException(CycloneDxException):
+    """Validation did not happen, due to missing dependencies."""
+    pass
diff --git a/cyclonedx/validation/__init__.py b/cyclonedx/validation/__init__.py
index 4afd457d..78c96845 100644
--- a/cyclonedx/validation/__init__.py
+++ b/cyclonedx/validation/__init__.py
@@ -15,17 +15,20 @@
 # SPDX-License-Identifier: Apache-2.0
 
 from abc import ABC, abstractmethod
-from typing import TYPE_CHECKING, Any, Optional
+from typing import TYPE_CHECKING, Any, Optional, Protocol
 
 if TYPE_CHECKING:
     from ..schema import SchemaVersion
 
 
-class MissingOptionalDependencyException(BaseException):
-    pass
+class ValidationError:
+    """Validation failed with this specific error.
 
+    Use :attr:`~data` to access the content.
+    """
+
+    data: Any
 
-class ValidationError:
     def __init__(self, data: Any) -> None:
         self.data = data
 
@@ -36,22 +39,29 @@ def __str__(self) -> str:
         return str(self.data)
 
 
-class _BaseValidator(ABC):
+class Validator(Protocol):
+    """Validator protocol"""
+
+    def validate_str(self, data: str) -> Optional[ValidationError]:
+        """Validate a string"""
+        ...
+
+
+class _BaseValidator(Validator, ABC):
+    """this class is non-public. changes without notice may happen."""
 
     def __init__(self, schema_version: 'SchemaVersion') -> None:
         self.__schema_version = schema_version
         if not self._schema_file:
             raise ValueError(f'unsupported schema: {schema_version}')
 
-    @property
-    @abstractmethod
-    def _schema_file(self) -> Optional[str]:
-        ...
-
     @property
     def schema_version(self) -> 'SchemaVersion':
+        """get the schema version."""
         return self.__schema_version
 
+    @property
     @abstractmethod
-    def validate_str(self, data: str) -> Optional[ValidationError]:
+    def _schema_file(self) -> Optional[str]:
+        """get the schema file according to schema version."""
         ...
diff --git a/cyclonedx/validation/json.py b/cyclonedx/validation/json.py
index e181443a..8b7cc1ee 100644
--- a/cyclonedx/validation/json.py
+++ b/cyclonedx/validation/json.py
@@ -20,8 +20,12 @@
 from json import loads as json_loads
 from typing import TYPE_CHECKING, Any, Optional, Tuple
 
+if TYPE_CHECKING:
+    from ..schema import SchemaVersion
+
+from ..exception import MissingOptionalDependencyException
 from ..schema._res import BOM_JSON as _S_BOM, BOM_JSON_STRICT as _S_BOM_STRICT, JSF as _S_JSF, SPDX_JSON as _S_SPDX
-from . import MissingOptionalDependencyException, ValidationError, _BaseValidator
+from . import ValidationError, _BaseValidator
 
 _missing_deps_error: Optional[Tuple[MissingOptionalDependencyException, ImportError]] = None
 try:
@@ -39,7 +43,16 @@
     ), err
 
 
-class __BaseJsonValidator(_BaseValidator, ABC):
+class _BaseJsonValidator(_BaseValidator, ABC):
+
+    def __init__(self, schema_version: 'SchemaVersion') -> None:
+        # this is the def that is used for generating the documentation
+        super().__init__(schema_version)
+
+    def validate_str(self, data: str) -> Optional[ValidationError]:
+        """Validate a string according to the schema version."""
+        # this is the def that is used for generating the documentation
+
     if _missing_deps_error:
         __MDERROR = _missing_deps_error
 
@@ -84,15 +97,20 @@ def __make_validator_registry() -> Registry[Any]:
                 ])
 
 
-class JsonValidator(__BaseJsonValidator):
+class JsonValidator(_BaseJsonValidator):
+    """Validator for CycloneDX documents in JSON format."""
 
     @property
     def _schema_file(self) -> Optional[str]:
         return _S_BOM.get(self.schema_version)
 
 
-class JsonStrictValidator(__BaseJsonValidator):
+class JsonStrictValidator(_BaseJsonValidator):
+    """Strict validator for CycloneDX documents in JSON format.
 
+    In contrast to :class:`~JsonValidator`,
+    the document must not have additional or unknown JSON properties.
+    """
     @property
     def _schema_file(self) -> Optional[str]:
         return _S_BOM_STRICT.get(self.schema_version)
diff --git a/cyclonedx/validation/xml.py b/cyclonedx/validation/xml.py
index 65a3e5ad..c7775546 100644
--- a/cyclonedx/validation/xml.py
+++ b/cyclonedx/validation/xml.py
@@ -17,10 +17,14 @@
 __all__ = ['XmlValidator']
 
 from abc import ABC
-from typing import Any, Optional, Tuple
+from typing import TYPE_CHECKING, Any, Optional, Tuple
 
+from ..exception import MissingOptionalDependencyException
 from ..schema._res import BOM_XML as _S_BOM
-from . import MissingOptionalDependencyException, ValidationError, _BaseValidator
+from . import ValidationError, _BaseValidator
+
+if TYPE_CHECKING:
+    from ..schema import SchemaVersion
 
 _missing_deps_error: Optional[Tuple[MissingOptionalDependencyException, ImportError]] = None
 try:
@@ -32,7 +36,16 @@
     ), err
 
 
-class __BaseXmlValidator(_BaseValidator, ABC):
+class _BaseXmlValidator(_BaseValidator, ABC):
+
+    def __init__(self, schema_version: 'SchemaVersion') -> None:
+        # this is the def that is used for generating the documentation
+        super().__init__(schema_version)
+
+    def validate_str(self, data: str) -> Optional[ValidationError]:
+        """Validate a string according to the schema version."""
+        # this is the def that is used for generating the documentation
+
     if _missing_deps_error:
         __MDERROR = _missing_deps_error
 
@@ -67,7 +80,9 @@ def _validator(self) -> 'XMLSchema':
             return self.__validator
 
 
-class XmlValidator(__BaseXmlValidator):
+class XmlValidator(_BaseXmlValidator):
+    """Validator for CycloneDX documents in XML format."""
+
     @property
     def _schema_file(self) -> Optional[str]:
         return _S_BOM.get(self.schema_version)
diff --git a/docs/conf.py b/docs/conf.py
index 9faa5c7a..5abdefc5 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -31,15 +31,18 @@
 # ones.
 extensions = [
     "sphinx.ext.autodoc",
-    "sphinx.ext.viewcode",
+    # "sphinx.ext.viewcode",
     "autoapi.extension",
     "sphinx_rtd_theme",
     "m2r2"
 ]
 
+
 # Document Python Code
 autoapi_type = 'python'
 autoapi_dirs = ['../cyclonedx']
+# see https://sphinx-autoapi.readthedocs.io/en/latest/reference/config.html#confval-autoapi_options
+autoapi_options = ['show-module-summary', 'members', 'undoc-members', 'inherited-members', 'show-inheritance']
 
 source_suffix = ['.rst', '.md']
 
diff --git a/docs/contributing.rst b/docs/contributing.rst
index ff1705b3..4fc50161 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -1,83 +1 @@
-Contributing
-====================================================
-
-Pull requests are welcome, but please read these contributing guidelines first.
-
-Setup
-----------------------------------------------------
-
-This project uses `poetry`_. Have it installed and setup first.
-
-To install dev-dependencies and tools:
-
-.. code-block::
-
-   poetry install --all-extras
-
-Code style
-----------------------------------------------------
-
-This project uses `PEP8`_ Style Guide for Python Code. This project loves sorted imports. Get it all applied via:
-
-.. code-block::
-
-    poetry run isort .
-    poetry run autopep8 -ir cyclonedx/ tests/ typings/ examples/
-
-
-Documentation
-----------------------------------------------------
-
-This project uses `Sphinx`_ to generate documentation which is automatically published to `readthedocs.io`_.
-
-Source for documentation is stored in the ``docs`` folder in `RST`_ format.
-
-You can generate the documentation locally by running:
-
-.. code-block::
-
-    cd docs
-    pip install -r requirements.txt
-    make html
-
-
-Testing
-----------------------------------------------------
-
-Run all tests in dedicated environments, via:
-
-.. code-block::
-
-    poetry run tox run
-
-
-Sign your commits
-----------------------------------------------------
-
-Please sign your commits, to show that you agree to publish your changes under the current terms and licenses of the
-project. We can't accept contributions, however great, if you do not sign your commits.
-
-.. code-block::
-
-    git commit --signed-off ...
-
-
-Pre-commit hooks
-----------------------------------------------------
-
-If you like to take advantage of `pre-commit hooks`_, you can do so to cover most of the topics on this page when
-contributing.
-
-.. code-block::
-
-    pre-commit install
-
-All our pre-commit checks will run locally before you can commit!
-
-
-.. _poetry: https://python-poetry.org
-.. _PEP8: https://www.python.org/dev/peps/pep-0008
-.. _Sphinx: https://www.sphinx-doc.org/
-.. _readthedocs.io: https://cyclonedx-python-library.readthedocs.io/
-.. _RST: https://en.wikipedia.org/wiki/ReStructuredText
-.. _pre-commit hooks: https://pre-commit.com
+.. mdinclude:: ../CONTRIBUTING.md
diff --git a/docs/requirements.txt b/docs/requirements.txt
index db0c3d0f..dfba7e14 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -1,4 +1,4 @@
 m2r2>=0.3.2
-Sphinx>=4.3.2
-sphinx-autoapi>=1.8.4
-sphinx-rtd-theme>=1.0.0
\ No newline at end of file
+Sphinx>=7.2.6,<8
+sphinx-autoapi>=2.1.1,<3
+sphinx-rtd-theme>=1.3.0,<2
diff --git a/examples/complex.py b/examples/complex.py
index f39460c3..f64b1652 100644
--- a/examples/complex.py
+++ b/examples/complex.py
@@ -1,5 +1,8 @@
 import sys
 
+from packageurl import PackageURL
+
+from cyclonedx.exception import MissingOptionalDependencyException
 from cyclonedx.factory.license import LicenseChoiceFactory, LicenseFactory
 from cyclonedx.model import OrganizationalEntity, XsUri
 from cyclonedx.model.bom import Bom
@@ -7,10 +10,8 @@
 from cyclonedx.output.json import JsonV1Dot4
 from cyclonedx.output.xml import XmlV1Dot4
 from cyclonedx.schema import SchemaVersion
-from cyclonedx.validation import MissingOptionalDependencyException
 from cyclonedx.validation.json import JsonValidator
 from cyclonedx.validation.xml import XmlValidator
-from packageurl import PackageURL
 
 lc_factory = LicenseChoiceFactory(license_factory=LicenseFactory())
 
diff --git a/tests/base.py b/tests/base.py
index a0bbb2b2..fff18cdf 100644
--- a/tests/base.py
+++ b/tests/base.py
@@ -28,8 +28,8 @@
 from xmldiff import main
 from xmldiff.actions import MoveNode
 
+from cyclonedx.exception import MissingOptionalDependencyException
 from cyclonedx.output import SchemaVersion
-from cyclonedx.validation import MissingOptionalDependencyException
 from cyclonedx.validation.json import JsonValidator
 from cyclonedx.validation.xml import XmlValidator
 
diff --git a/tests/test_validation_json.py b/tests/test_validation_json.py
index 2e919e60..ab00304e 100644
--- a/tests/test_validation_json.py
+++ b/tests/test_validation_json.py
@@ -24,8 +24,8 @@
 
 from ddt import data, ddt, idata, unpack
 
+from cyclonedx.exception import MissingOptionalDependencyException
 from cyclonedx.schema import SchemaVersion
-from cyclonedx.validation import MissingOptionalDependencyException
 from cyclonedx.validation.json import JsonStrictValidator, JsonValidator
 
 from . import TESTDATA_DIRECTORY